For a user with healthy eyes, when viewing a relatively small or relatively far object, it is hard to observe desired details by the eyes. For example, when people sit at a relatively far position watching a ball game, it is hard to observe the details of body motion and emotional expression of a player. For a user whose eyes already have problems of myopia or hypermetropia, when viewing a relatively small or relatively far object, it is harder to identify the details of an observed object or person by the eyes. On the other hand, when viewing a relatively large or relatively near object, it is hard to observe the panorama information of the gazed object. For example, when a user stands in front of a high building or a big mountain, it is hard to observe their panorama.
Conventional optical zooming devices, such as a telescope or a magnifier, rely on manual setting of zooming parameters, and are not convenient for use.